1. Field of the Invention
The present invention relates to a fluid dynamic bearing device and a method of manufacturing the same.
2. Description of Related Art
A fluid dynamic bearing device is a bearing device that rotatably supports a shaft member with a fluid film of a lubricating fluid formed in a bearing gap. The fluid dynamic bearing device is one having characteristics such as high-speed rotation, excellent rotational accuracy, and quietness. In recent years, by taking advantage of those characteristics, the fluid dynamic bearing device is suitably used as a bearing device for a motor to be mounted to various electrical apparatuses such as information equipment. Specifically, as a bearing device for a motor, the fluid dynamic bearing device can be suitably used in the following: a spindle motor for an information apparatus such as a magnetic disk drive such as an HDD, an optical disk drive for a CD-ROM, CD-R/RW, DVD-ROM/RAM, or the like, or a magneto-optical disk drive for an MD, MO, or the like; a polygon scanner motor of a laser beam printer (LBP); a color wheel motor for a projector or the like; or a fan motor.
A well-known example of the fluid dynamic bearing device incorporated in a spindle motor for a disk drive or the like is illustrated in FIG. 7. A fluid dynamic bearing device 70 illustrated in the figure includes a bearing sleeve 78 fixed to an inner periphery of a housing 77, a shaft member 72 inserted into an inner periphery of the bearing sleeve 78, and radial bearing parts 75, 76 provided in radial bearing gaps between an outer peripheral surface of the shaft member 72 and an inner peripheral surface of the bearing sleeve 78. In terms of cost-reduction of the fluid dynamic bearing device, it is desirable that the number of components be as small as possible, and that shapes of the members be as simple as possible. In this context, in the fluid dynamic bearing device 70 illustrated in the figure, the housing 77 is formed in a bottomed cylindrical shape (cup shape) in which a side part and a bottom part are integrated with each other (refer to Patent Documents 1 and 2, for example).
Patent Document 1: JP 2003-232353 A
Patent Document 2: JP 2003-239974 A